Mortar latex mix

Abstract

Improved Portland cement compositions are provided by the use of a combination of additives which increase plasticity and allow the use of less water. When the mixture is cured or set, the resultant concrete has higher compressive strength, higher flexural and shear strength, is believed to be markedly less susceptible to penetration by moisture or corrosive liquids, and have greater freeze-thaw stability. Such concrete is highly advantageous in thin paving sections such as bridge deck overlays, overpasses, elevated freeways and the like. The preferred additives are a latex of a styrene-butadiene containing polymer and a dispersing agent such as a polymerized naphthalene sulfonic acid or a salt thereof.

What we claim is: 
     
       1. A process of producing a concrete paving which comprises: (a) preparing a cement mortar composition of Portland cement, aggregate, water, from about 1 to about 15 parts by weight on a dry weight basis per 100 parts of cement of a latex of a polymer comprising from about 40 to 70 parts by weight of styrene, from about 60 to 30 parts by weight of butadiene, from about 0.5 to about 5.0 parts of N-methylolacrylamide by weight of said polymer, or from about 0.5 to about 5.0 parts by weight each of N-methylolacrylamide and acrylonitrile by weight of said polymer, said parts in total of N-methylolacrylamide and acrylonitrile being from about 1.0 to about 6.0 parts by weight of said polymer, and a dispersing agent being a polymerized or condensed alkyl substituted or unsubstituted naphthalene sulfonic acid or salt thereof in an amount of from about 0.5 to about 8 weight percent of the polymer content of said latex; which composition provides increased compressive and flexural strength when cured and permits a reduction in the water content thereof while providing a plastic flowable mix;   (b) applying the mixed composition as a layer to a pavement sub-base; and   (c) curing the pavement.   
     
     
       2. The process of claim 1 wherein said dispersing agent is a sodium salt of a condensed mononaphthalene sulfonic acid. 
     
     
       3. The process of claim 1 wherein said dispersing agent is added in an amount from about 3 to about 4 weight percent of the polymer content of said latex. 
     
     
       4. The process of claim 1 wherein said styrene-butadiene ratio is from about 60:40 to about 67:33. 
     
     
       5. The process of claim 1 wherein said polymer is a styrene-butadiene polymer containing from about 1.0 to about 3.0 parts of N-methylolacrylamide by weight of said polymer or from about 1.0 to about 3.0 parts each of N-methylolacrylamide and acrylonitrile by weight of said polymer, said parts in total of N-methylolacrylamide and acrylonitrile being from about 2.0 to about 5.0 parts by weight of said polymer.